Electric switch



Oct. 5, 1937. I G. o. WlLMS ELECTRIC SWITCH Filed Nov. 26, 1934 4Sheets-Sheet l 83W GUS/5v U M/ma Oct. 5, 1937.' O wlLMS 2,095,222

ELECTRIC SWITCH Filed Nov. 26, 1934 4 Sheets-Sheet 2 MW L 51 5251/ U]W/zzzs Oct. 5, 1937.

e. o. WILMS 2,095,222

ELECTRIC SWITCH Filed Nov. 26, 1934 4 Sheets-Sheet 3 [FL 512W Z7 M/mOct. 5, 1937. 5, Q w s 2,095,222

ELECTRIC SWITCH Filed Nov. 26, 1934 4 Sheds-Sheet 4 .EL/S/HI/ Z7. M/msPatented Oct. 5, 1937 UNITED STATES PATENT OFFICE ELECTRIC SWITCH Gustav0. Wilms, Milwaukee, Wis., assignor to Allen-Bradley Company, Milwaukee,Wis., a corporation of Wisconsin Application November 26, 1934, SerialNo. 754,737

27 Claims. (01. 200-116) jected has compelled the use of cheaper motorswhich are incapable of withstanding large overloads. Consequently, theprovision of reliable quick acting overload protection is of utmostimportance, but again the necessity for low cost requires that theoverload protective device employed should be inexpensive. Likewise, the

' switch for turning the motor on and off must be reliable, butinexpensive.

To meet this demandfor low cost, the overload release and the on and offswitch are usually combined in a single unit, which to be at allpractical and commercially successful must have the followingqualifications:

, In the first instance, the unit must be inexpensive; it must becompact and mechanically strong throughout; its overload responsivefeature must be reliable and accurate; its switch must be snap acting;it must trip free upon an overload so that under no circumstances canthe switch be held closed under sustainedmotor overload conditions; itshould have an indicator to show whether or not the switch is closed andalso whether or not it has been tripped in re-' spouse to an overloadcondition; and, for the sake of simplicity, a single operating membermust provide for opening and closing the switch and also for resettingthe overload release.

It is therefore a general objectof this invention to provide a combinedmanually operable and overload responsive switch which has all of theforegoing qualifications.

Heretofore, all overload release mechanisms were of such constructionand design that a unit having all of the desirable qualificationsmenrelease permits considerable strain to be placed directly on thefusible alloy held latch itself, and because of its comparatively highaccuracy, this type of. overload release is employed in this invention.

With a view toward compactness, it is a more specific object of thisinvention to provide an overload responsive latch unit which embodies ina single small structure, a contact for the switch, a latch releasablyheld by a fusible alloy, a heater to melt the alloy, and an enclosurefor the heater.

A further object of this invention resides in the provision of novelmeans for associating a snap switch with an overload tripping mechanismso that a. single set of switch contacts opens 'and closes the motorcircuit in response to manual operation of the switch and also opens themotor circuit in response to an overload condition.

Another object of this invention resides in the provision of resettingmeans for the overload release so associated with the snap switch thatthe operating member of the snap switch also provides means forresetting the overload release mechanism. 1

Another object of this invention is to provide an indicator whichactsdirectly in conjunction with the opening and closing of the switchindependently of the operating means therefor so that through adiscrepancy between the indication of the indicator and the position ofthe operating member for the switch, the fact that the switch has beentripped in response to an overload is shown.

A further object of this invention is to provide a tripping mechanismoperable in response to an overload conditionwhich will trip the switchentirely free from and independently of the operating means for theswitch so that in no event can the switch be held closed under sustainedmotor overload conditions.

With the above and other objects in view which will appear as thedescription proceeds, this invention resides in the novel construction,cominvention constructed according to the best mode so far devised forthe practical application of the principles thereof, and in which:

Figure 1 is a perspective view of the switch combinatlon'forming thesubject matter of this invention, part of the cover being broken away;

Figure 2 is a longitudinal section view through Figure 1 on the plane ofthe line 2-2;

Figure 3 is an enlarged side view illustratin the side of the switchopposite that shown in Figure 2;

Figure 4 is a perspective view of the switch and overload releasemechanism removed from the Supporting base;

Figure 5 is a view similar to Figure 3 but showing the switch open andwith part of the latch unit and stationary contact broken away;

Figure 6 is an enlarged longitudinal section view through the latch unitand stationary contact; Figure 7 is a top view of the latch unit andstationary contact showing particularly the ratchet wheel and the triplever which is held in its potentially operative position by the ratchetwheel;

Figure 8 is a perspective view of the two halves of the switch frame;

Figure 9 is a. perspective view of the indicator arm;

Figure 10 is a perspective view of the movable contactor;

Figure 11 is a perspective view of the operating lever; and

Figure 12 is a side view of the spring which provides contact pressureand holds the contactor in open or closed position.

Referring now more particularly to the accompanying drawings in whichlike numerals indicate like parts throughout the several views, thenumeral 5 represents a base of insulating material having its front facehollowed out for the reception of a snap switch unit indicated generallyby the numeral 6. The switch is manually operable by a pivoted lever 1projecting through an opening 8 in a cover 9 mounted on and closing theopen front of the base.

The cover is held to the base by a screw l6,

' threaded in an elongated nut I I received in a dental detachment ofthe screw ID from the cover a fiber washer I4 is frictionally engagedwith the screw, as shown.

The switch 6 is assembled on a stamped metal 7 frame l6 composed of twosimilar sections I7 and I 8 (see Figure 8) each of which has a side wall19 and an end wall 26. The side walls have tangs 2| projecting therefromto be secured in holes 22 in the end wa1ls'26 to secure the sections l1and I8 together.

The frame is mounted on the base with the inner edges of its end walls20 resting on shelves 23 formed by the configuration of the recess inthe base into which the frame fits. To hold the frame against shiftinglaterally, tangs 24 project from its end walls 20 into recesses openingto the shelves 23. To secure the frame to the base, the inner ends ofits side walls have tangs 25 which pass through an'opening in the bottomof the base to project through and be secured to a plate 26 fixed in acavity 27 at the back of the base.

The cavity 21 opens to the back of the base and communicates with theopening through which the tangs 25 pass. Its dimension transversely ofthe base is greater than the width of the opening so that the ends ofthe plate 26 are securely supported against forward movement. Theattachment of the tangs 25 to the plate maybe effected in any desiredmanner, but is conveniently accomplished'by twisting their outer ends asillustrated. After the attachment has been made, the cavity 21 may befilled with a suitable sealing substance 26.

The side walls of the frame have aligned open-- ings 29 and 30 locatednear the front and rear of the frame, respectively. The openings 29provide bearings for pivotally mounting the lever 1, and the openings 30provide bearings for pivotally mounting a movable contactor armindicated generally by the numeral 3 I Both the piv-. oted lever 'I andthe contactor arm, 3! have por tions disposed between the sides of theframe and are mounted from the holes 29 and 36 in a manner to behereinafter described.

Besides the small bearing openings 29 and 30, the side walls of theframe also have large irregularly shaped openings 32, the edges at thefront and rear ends of which provide stops for limiting the movement ofthe lever! and the contactor arm 3 l The lever 'i is stamped from sheetmetal and has trunnions 33 projecting laterally from its side edges toengage in the openings 29 and pivotally mount the lever. Fixed to theouter end of the lever is a handle 34 molded of insulating material andof a size to substantially close the hole 8 in the cover.

. Preferably, the handle 34 is slipped onto the lever l and is secured.thereon either frictionally or by means of a suitable. cement ratherthan by being molded directly onto the end of the lever.

As best illustrated in Figures 1 and 2, the position of the pivotal axisof the lever 1 is such that at its limits of movement, one or the otherof two inclined faces 35 and 36 on the handle portion 34 is visiblethrough the opening 8. The face 35 carries the designation On, and theface 36 has the designation Off so as to visually indicate the positionof the lever I.

To insure proper assembly of the handle portion 3 3 with the lever 7;the lever is bent adjacent its pivotal axis so that its opposite endportions are disposed slightly angular to each other, and one of the twoforks 3'7, into which the inner portion of the handle 35 is divided toprovide the inclined faces 35 and 36, has its opposite edge portions cutaway as at 38.

Consequently, itis-possible to completely engage the handle portion 34with the metal part of the lever only in one position. without havingone of the forked inner portions 31 of the lever strike the adjacentfront edges of the frame when the lever is in one of its two positions.When the handle'portions 34 is properly assembled with the lever,neither of the two forks 31 strikes the front edges of the frame, therecesses 38 providing the clearance in one position of the lever.

To define the range of angular movement of the lever I, lateralprojections 39 and 40 on the sides of the lever engage with the stopsprovided by the front edges 4| of the openings 32 in the frame sides. a

As best shown in Figure 11 the innermost extremity of the lever 1 has acentral tongue 42 projecting from two knife edges 43 at opposite sidesof the tongue, and a rivet 44 having rounded heads secured in the tongueadjacent its outer end portion so that the tongue has substantially abulbous shape.

Engaged over the bulbous inner end of the lever l and bearing on theknife edges 43 is one end of a compression spring 66. The other end ofthe compression spring bears against part of the contactor arm 3|. Thedistance between the portions of the lever I and the contactor armagainst which the opposite ends of the spring bear is less than theexpanded length of the spring in any position of the parts so that thespring is at alltimes in compression, and as hereinafter described,snaps the contactor arm from one position to theother as the lever l ismoved.

The contactor arm 3|, as best illustrated in Figure 10, is stamped fromsheet metal and has a flat mounting portion 48 provided with anangularly disposed flange 49 bent up from one edge thereof. The flange49 has an overhanging projection 59 from the outer end of which a fingeri projects laterally to be disposed in a plane substantially parallelwith the plane of the mounting portion 48. The outer end of the finger5i has a contact 52 fixed thereto, and projecting from the opposite sideedges of the fiat mounting portion 48 are aligned tangs 53 and 54, re--spectively. These tangs are received in the rear openings 30 in the sidewalls of the frame to pivotally mount the contactor arm.

The front edge of the flat mounting portion 48 has a tongue 55 toproject into the adjacent end or the spring 46 and two knife edges 58 atopposite sides of the tongue to provide bearing surfaces for the spring.To assist the tongue 55 to maintain the spring properly engaged with theknife edges 56, the adjacent endmost coil of the spring instead of beingflat and perpendicular to the axis of the spring as is ordinarily thecase, is bent to lie in twoangularly disposed planes as clearly shown inFigure 12.

The limits of swinging movement of the contactor arm 31 are defined bythe engagement of a tang 51 projecting from the edge of the mountingportion 48 alongside the tang 53, with the inner or rear edges 58 of theopenings 32 in the frame side walls. I

It is to V be noted that the arcuate distance of the permitted angularmotion of the contactor arm is less than that of the lever 1.Consequently, when the lever 1 is actuated from one limit of movement tothe other, the fulcrum provided by the knife edges 43 on the inner endof the lever l swings across dead center to shift the line of force ofthe spring so that the spring snaps the contactor arm to its oppositeposition.

The tangs 53 and 51 extend a substantial distance beyond the side of theframe to mount an indicator 59. This indicator 59 may be formed of fiberand is attached to the arms 53 and 51 by having the outer shoulderedportion of the tang 51 received in a hole 60 and the extremity of thetang 53 engaged in an open recess 6| in the inner end of the indicator.The outer end of the indicator is enlarged as shown in Figure 9 andis sopositioned as to be visible through the hole 62 in the cover.

When the movable contactor is in its oil? position, the indicator isinclined upwardly with. respect to the horizontal as shown in Figure 5to bring its lower white or light colored portion 63 in line'with theopening 62, while in the opposite or on position of the contactor, theblack or dark colored upper portion 64 of the indicator only is visiblethrough the opening 62. Hence the indicator shows white when the switchcontacts are disengaged, and inasmuch as the indicator moves with thecontactor arm independently of the actuating lever I, it indicates whenthe switch has been tripped by the overload release to be laterdescribed.

The contact 66 is mounted on and forms part of a latch unit indicatedgenerally by the numeral 61. This unit is mounted on the base alongsidethe switch mechanism by a bracket 68 which,

of the bracket and a nut 13 threaded on its outer end serves to readilydetachably clamp the bracket to the flange of the terminal. Aninterengaging tongue and groove connection 14 and i5 on the fianges B9and Hi, respectively, holds the bracket against turning about the axisof the screw.

'As will be more at length described hereinafter,

there is an electrical connection between the bracket 68 and thestationary contact 66 and inasmuch as the bracket 68 is directly engagedwith the terminal II electrical connection from the terminal to thestationary contact 66 is afforded.

Electrical connection to the movable contactor is provided by a secondterminal 11 fixed to the base by a screw '18 on the opposite side of theswitch mechanism. This terminal 11 is connected through a flexiblejumper 19 to the contactor arm, the ends of the flexible jumper beingsoldered directly to the terminal and the contactor arm.

Between the terminals IL and i1 and beneath the-switch mechanism, thebase has an opening 19 through which conductor wires may be passed forattachment to the terminals in the conventional manner.

The mechanism described thus far comprises a complete manually operablesnap switch particularly adapted for starting and stopping smallelectric motors. Combined therewith is an overload responsive trippingmechanism indicated generally by the numeral 80, to open the switchentirely independently ofthe manual control therefor in response to anoverload condition so as to afford overload protection for the motorwith which the switch is used. A novel feature of the combinationresides in the fact that a single set of contacts is used for both themanual control of the motor circuit and also for the automatic openingof the circuit in the event of an overload.

The tripping mechanism comprises a substantially T shaped lever 81preferably of insulating material, and pivotally mounted at the end ofits stem on a trunnion 82 projecting from the side of the terminalflange Ill. One end 83 of the head of the T shaped lever is arranged toengage the overhangingportion 50 of the movable contactor arm to swingthe movable contactor about its pivotal mounting and disengage itscontact 52 from the stationary contact 66. To effect this motion of thelever 81, a torsion spring 85 is provided- The spring 85 is coiled aboutthe trunnion 82 and has one end hooked onto the lever as at 86 and itsother end bearing against a lug 81 integral with the terminal flange 10'and disposed a short distance from the trunnion 82.

Fixed to the head of the lever BI is a spring pawl 88, the outer end ofwhich is bent to provide a. spring finger 89 adapted for engagement withthe teeth of aratchet wheel 90 forming part of the latch unit 61.Normally, the ratchet wheel 90 is fixed against rotation so that withthe spring finger of the pawl engaged therewith, as best shown in Figure7, the lever 8| of the tripping mechanism is held against movement in apotentially operative position. To move the lever 8| to this positionand thereby provide means for resetting the tripping mechanism, theprojection '40 on the lever 1 extends sumciently far beyond the adjacentside wall of the switch frame to engage the head of the T shaped leverduring movement of the lever I to its ofi position. Hence, to reset thetripping mechanism, it is only necessary to push the lever I to its offposition as indicated by the legend 92 on the front of the cover. I I

The latchunit 61, as bestillustrated in Figure. 6, comprises a cup 94fixed to the shelf of the bracket 68, within which a hollow post 95 is IThe upper closed end of the hollow post 95 has I the stationary contact66 sweated or otherwise flxed thereto, but inasmuch as the post 95 isinsulated from the cup 94, and consequently the bracket, there is nodirect electrical connection from the bracket to the stationary contact.The only connection from the bracket to the station- .ary contact isthrough a heater coil 98 disposed within thehollow of the post 95 withone end fixed in the closedupper end portion of the post 95 to have goodelectrical connection with the contact 66, and its other end passed downthrough a hole 99 in the bottom of the cup 94 to be embedded in a weldof solder I00 which also serves upper end of the post 95. The wheel 90is journalled on the upper reduced. end of the post and is held againstendwise movement by a. shoulder I03 and a spring ring I04 engaged underthe overhanging peripheral edge of the contact 661' Normally, the solderI02 secures the ratchet wheel against rotation, but when the currentpassing through the heater coil exceeds the pre- "determined value, theheat generated therein melts the solder and frees the ratchet wheel forrotation; Consequently, upon the occurrence of an'overload condition inthe circuit closed by the switch, the tripping mechanism is released andinasmuch as its spring 85 is stronger than the spring 46, the switch isautomatically opened.

, During the opening of the switch by the tripping mechanism, theposition ofthe'manually operable lever I is not disturbed. The indicatorarm, however, moving with the movable contactor is swung to its positionat which the white por; tion thereof is. visible through the hole Iii-toindicate that the switch isopen. There is thus a.

discrepancybetween the indicator and the visible .designation of thelever], one indicating that the switch is closed and theother that/ theswitch is open. This indicates that "the switch has been tripped inresponse to an overload condition and?" that to'reclose the switch it isnecessaryto first move the lever 'I to its resetting position whichstillexists the switch will again be opened by the thermal release of thetripping mechanism.

From the foregoing description taken inconnection with the accompanyingdrawings, it will be readily apparent to those skilled in the art towhich this invention appertains, that this invention provides a novelcombination of snap switch and overload protection for smallelectric'motors, and that in utilizing the same set of contacts foropening and closing the circuit manually and opening the circuit inresponse to an overload, and in providing a single compact unit to formboth the mounting for the stationary contact and the latch for thetripping mechanism of the overload release, exceptional compactness isachieved. .The construction of the latch unit is particularly conduciveto compactness and simplicity of design, for it not only afiordsreduction in size of the elements which comprise its assembly, but italso provides an improved thermal latch for the fusible alloy type ofoverload release.

What I claim as my invention is:-' I

1. In a combined manually operable and overload responsive switch, astationary contact, a terminal for the stationary contact, a movablecontactor engageable with the stationary contact, manually operablemeans to eifect actuation of the mo'vableicontactor into and out ofengage.-

' ment with the stationary contact, a tripping lever for disengaging themovable contactor from the stationary contact independently of said manually operable means, means on said terminal to pivotally mount thetripping lever, a spring acting on the tripping lever and biased to aposition at all times yieldably urging the trippinglever into engagementwith the movable contactor,- and releasable latch means to hold thetripping lever in an inactive potentially operative position with itsspring under tension.

to hold the ratchet wheel stationary, a heater to melt the fusiblemeans, and common means to mount the ratchet wheel, the heater and saidother contact from the base.

3. A switch of the character described comprising a stationary contact,a movable contactor engageable with the stationary contact, a manuallyoperable member to effect actuation'of "the-,movable contactorto andfrom engagement with the stationary contact, a contact spring directlyconnecting the movable contactor and said manually operable member tosnap the movable contactor from one position to the other as themanually operable member is actuated, tripping mechanism fordisengaging. the movable contactor from the stationary'contactindependently of the manually operable member and the contactspring,said tripping mechanism including a v ,spring of .suficient strength tooverpower the contactspring and move the actuator to its off positioneven though the contact spring con- *tinu'es to urge the Contact to itson 'position,'

andlatch means for 'releasably holding the trippinggm-eohanism in apotentially operative position with'its spring under tension,

4. A switch of the character described comprising a stationary contact,a movable'contactor e geable with the stationary contact, a I

manually operable member to efi'ect actuation of" themovable contactor.to and from engagement 75- with the stationary contact, a contactspring directly connecting the movable contactor and said manuallyoperable member to snap the movable contactor from one position to theother as the manually operable member is actuated, tripping mechanismfor disengaging the movable contactor from the stationary contactindependently of the manually operable member and the contact spring,said tripping mechanism including a spring of suflicient strength tooverpower the contact spring and move the contactor to its oil positioneven though the contact spring continues to urge the contactor to its onposition, latch means for releasably holding the tripping mechanism is apotentially operative position with its spring under tension, and meansconnected in series with the stationary contact and movable contactor tobe influenced by electric current flowing therethrough for releasing thelatch means-upon the passage therethrough of current in excess of apredetermined value.

5. In a switch of the character described, a base, cooperating contactsto be engaged and disengaged, manually operable means to engage anddisengage the contacts, tripping mechanism to efl'ect disengagement ofthe contacts independently of the manually operable means, said trippingmechanism including a spring and a pawl, a releasable latch in the formof a ratchet wheel engageable by the pawl to hold-.the trippingmechanism in a potentially operative position with its spring undertension, a common supporting post to mount the ratchet wheel and one ofthe con.- tacts from the base, and means responsive to a predeterminedcondition for releasing the ratchet wheel for rotation on its supportingpost.

6. A switch of the character described comprising a base, cooperatingcontacts to be engaged and disengaged, manually operable means to engageand disengage thecontacts, tripping mechanism to effect disengagement ofthe contacts independently of the manually operable means, said trippingmechanism including a spring and a pawl, a releasable latch in the formof a ratchet wheel engageable by the pawl to hold the tripping mechanismin a potentially operative position with its spring under tension, acommon supporting post to mount the ratchet wheel and one of thecontacts from the base, and means, enclosed within said post andresponsive to a predetermined condition for releasing the ratchet wheelfor rotation about the post.

7. A switch of the character described comprising a stationary contact,amovable contactor, means mounting the movable contactor for movement toand from engagement with the stationary contact, a manually operableactuator, a spring connecting the actuator and the movable contactor andadapted to snap the movable contactor from one position to the other asthe actuator is moved, and tripping mechanism to disengage, the movablecontactor from the stationary contact, comprising a pivoted lever havinga part engageable with the movable contactor to move the same out ofengagement with the stationary contact, a spring for moving said pivotedlever to, cause the same to disengage the movable contactor from thestationary contact, and latch means to releasably hold the pivoted leverin a potentially operative position with its spring under tension.

8. In a combined manually operable and overload responsive switch, astationary contact, a post mounting the stationarycontact, a terminalfor the stationary contact, a bracket to which the post is secured,means for readily detachably mounting the bracket in direct contact withthe terminal, a movable contactor, manually operable means to efiectactuation of the movable contactor into and out of engagement with thestationary contact, a tripping lever for swinging the movable contactorout of engagement with the stationary contact, a tang on the terminal onwhich the tripping lever is pivotally mounted, a spring to swing thetripping lever into operative engagement with the movable contactor, andthermally responsive latch means mounted on the supporting post of thestationary contact for releasably holding the tripping lever inactive ina potentially operative position.

9. In a combined manually operable and overload responsive switchincluding a movable cona contact at the closed end of'the post, aratchet wheel journalled on the post, a fusible alloy normally securingthe ratchet wheel against rotation on the post, and a heater coildisposed within the hollow of the post and having electrical connectionwith the bracket and the closed end of the post to conduct current fromthe bracket to the contact, the heat generated in said heater coil uponthe passage of excessive current therethrough melting the fusible alloyto release the ratchet wheel for rotation on the post.

11. As a separate article of manufacture, a combined latch unit andstationary contact comprising a hollow post open at one end, a mountingcup closing the open end of the post but electrically insulatedtherefrom, means engaged with the mounting cup to support the entireunit, the closed end of the post having a contact surface, a latchmember journalled on the post, a fusible alloy normally securing the.latch member against rotation on the post, and a heater coil having oneend electrically connected with the closed end of the post and its otherend electrically connected with said cup to carry current from the cupto the contact surface at the closed end of the post, said post beingthermally influenced by the temperature of the heater coil whereby thepassage of excessive current through the heater coil melts the fusiblealloy and releases the latch member for rotation on the post.

12. In a combined manually operable and overload responsive switch, aunitary structure affording both a thermally responsive latch and astationary contact comprising a hollow post having one open end and oneclosed end, means at the closed end affording a contact, a releasablelatch member journalled on the post, a fusible alloy normally securingthe latch member against rotation on the post, a cup closing the openend of the post, means to electrically insulate the cup from the post,means engaged with the cup to mount the structure, a heater coildisposed within the hollow at the po t and havin one end fixed to theclosed end of the post'and its other end electrically connected with theSupporting means for the cup whereby electric current may be passedthrough said supporting means and the coil to said contact portion, anda refractory material filling the hollow of the post and having theheater coil embedded therein to transmit heat from the coil to the post,whereby upon the passage of excessive current through the heater coilthe fusible alloy melts to release the latch means.

13. A latch unit for fusible alloy type overload release mechanismscomprising a rotatable latch member, a hollow post on which therotatable latch member is mounted, a fusible alloy normally securing thelatch member against rotation on the post, and a heater elementcontained within the hollow of the post to melt the fusible alloy andrelease the latch member for rotation.

14. A latch unit of the character described comprising a fixed hollowstern, a ratchet wheel journalled on the stem, a fusible alloy normallysecuring the ratchet wheel against rotation on the stem, and a heaterelement housed within the hollow of the stem and adapted to melt thefusible alloy to release the ratchet wheel for rotation.

15. A latch unit of the character described comprising a hollow stem, alatch member movably mounted on the hollow stem, a fusible alloynormally holding the latch member fixed to the stem, and a heaterelement enclosed within the hollow of the stem to melt the fusible alloyand release the latch member for movement.

16. A latch unit of the character described comprising a hollow post,means in direct electrical connection with the post for closing one endthereof, means electrically insulated from the post for closing theopposite end thereof, a movable latch member mounted on the post, afusible alloy normally securing the latch member against motion on thepost, and a heater element contained within the hollow of the post andhaving its opposite ends connected with the means closing the ends ofthe post to conduct electric current from one of said means to theother, the passage of an excessive current through the heater elementcausing the heater element to genv erate sufiicient heat to melt thefusible alloy and release the latch member.

1'7. A switch of the character described comprising, a stationarycontact, a movable contactor, a frame in which the movable contactor ismounted for swinging movement into and out of engagement with thestationary contact, a manually operable lever pivoted in said frame,spring means directly connecting the manually operable lever and themovable contactor to snap the movable contactor from one position to theother as the pivoted lever is moved from one limit of movement to theother, a tripping lever pivotally mounted adjacent the. frame to strikethe movable contactor and disengage it from the stationary contact, aspring to cause the tripping lever to strike the contactor, a releasablelatch to hold the tripping lever in its potentially operative positionwith its spring under tension and ready to cause the tripping lever tostrike the movable contactor, and means on the manually operable pivotedlever engageable with the tripping lever to swing the same on itspivotal mounting so as 1to reset the tripping lever after release fromits atch.

18. In a snap switch, a base having its front face hollowed out, a coverto close the front of the base and cooperate therewith to form ahousing, a stationary contact'mounted on the base within the housing, amovable contactor, a frame having spaced side walls fixed on the base, amovable contactor having a part disposed between the side walls andpivotally mounted therefrom for movement into and out of engagement withthe stationary contact, a manually operable lever projecting through ahole in the cover and having its innersend received between the sidewalls and pivotally mounted therefrom, a compression spring confinedbetween the inner end of the manually operable lever and the portion ofthe movable contact disposed between the side Walls to snap the movablecontactor into and out of engagement with .-the stationary contactuponmovement of the manually operable lever, cooperating means on themanually operable lever and one of the side walls to define the limitsof movement of said Lever, cooperating means on the movable contactorpart between the side walls of theframe and one of said side walls todefine the limits of movement of the. movable contactor, and anindicator movable with the movable contactor and havi g a part visiblethrough an opening in the cove of the contactor.

19. In a snap switch, a base, a cover cooperating with the base toprovide a housing, a stationary contact mounted on the base, a movablecontactor, a frame having spaced side walls mounted on the base, themovable contactor having a part disposed between the side walls of theframe, tangs extendinglaterally from the side edges of said movablecontactor part and received in aligned holes in the side walls of theframe to pivotally mount the movable contactor for swinging movement toand from engagement with the stationary contact, a manually operablelever having its outer end'projecting through a hole in the cover andits inner end portion received between the side walls of the frame,tangs extending laterally from the side edges of said inner portions ofthe lever and journalled in holes in the side walls of the frame topivotally mount the lever, a compression spring confined between theinner ends of said contactor part and the pivoted lever between the sidewalls of the frame to snap the movable contactor from one position tothe other as the pivoted lever is moved, a tang extending sidewise fromthe pivoted lever and to visually indicate the position engageable withstops formed on one of the side walls to limit its angular distance ofmotion, a tang extending from the side edge of said movable contactorpart between the side walls and engageable with stops on the adjacentside wall to define the limits of movement of the contactor,

and an indicator carried by said last named tang and the adjacenttrunnion of the movable contactorto swing with the movable contactor,said indicator having a part visible through a. hole in the cover tovisually indicate the position of the movable contactor.

20. In an electric switch, a movable contactor, a manually operableactuator to move the contactor to and from circuit closing position,means entirely independent of the manually operable actuator forautomatically tripping the contactor to an off position, visualindicating means on the actuator to indicate the position to which thecontactor has been moved by the actuator, and other indicating meansmovable with the contactor independently of the actuator and visiblewhenever the contactor is in its "ofi position, whereby a discrepancybetween the first and second named indicating means indicates that thecontactor has been tripped automatically.

load responsive switch, a housing having two openings through an outerwall thereof, a contactor movable between on and off positions, amanually operable actuator operable from the exterior of the housing andconnected with the contactor. to move the same from one position to theother, overload responsive means for automatically tripping thecontactor independently of' the manually operable actuator to move thecon-' tactor to its on position, indicating means on the actuatorvisible through one of the openings in the housing wall for indicatingthe position to which the contactor has been moved by the actuator, anda second indicating means movable with the contactor and visible throughthe other opening when the contactor is in itsoif position so that by adiscrepancy between the two indicating means with the indicating meanson the actuator showing on and the indicating means movable with thecontactor showing off the fact that the switch has been automaticallyopened in response to an overload is indicated.

22. In an electric switch having stationary and movable contacts,manually operable means to move the movable contact and effect openingand closing of the switch, primary spring means actuatable by themanually operable means to move the movable contact with a snap; andsecondary spring means operable upon the occurrence of a predeterminedcondition to move the movable contact out of engagement with thestationary .contact entirely independently of the primary spring meanswhich continues to urge'the movable contact toward the stationarycontact.

23. In an electric switch, stationary and movable contacts, an actuatorto effect movement of the movable contact, primary spring meansactuatable by the actuator and adapted to move the movable contact witha snap, a member movable 40 to push the movable contact out ,ofengagement with the stationary contact, and secondary spring meansreleased for operation upon overload to move said member and cause it topush the movable contact out of engagement with the stationary contact.

moved by the secondary spring means and adapted to push the contactcarrying member so as to disengage the movable contact from thestationary contact with a snap.

25-. In an electric switch, cooperating contacts, a hollow stem mountingone of the contacts, a latch member movablymounted on the hollow stem, afusible alloy normally securing the latch member against movement onthe'stem,

and a heater element enclosed within the hollow of the stem to melt thefusible alloy and release the latch member for movement, one end of saidheater elementbeing electrically connected with said designated contactto be connected in the circuit controlled by the contacts so thatcurrent flowing from one contact to the other flows through the heaterelement. J

26. As a separate article of I manufacture a combined latch unit andcontact for use with an overload responsive switch, comprising a hollowstem, a latch member journaled onothe stem, a fusible alloynormally'securing the latch memvber tothe stem, a heater elementcontained within the hollow ofthe stem to melt the fusible alloy andrelease the latchmember for rotation, and a part carried by the stem toprovide a switch contact and having one end of the heater elementelectrically connected thereto.

27. In an electric switch, cooperating movable and stationary contacts,a ,hollow stem mounting the stationary contact, a ratchet wheeljournaled on the stem, a fusible alloy normally securing the ratchetwheel against rotation on the stem, and a heater element housed withinthe hollow of the stem and adapted to melt the fusible alloy to releasethe ratchet wheel for rotation, said heater element being electricallyconnected with the stationary contact so that the contacts and theheater element may be connected in one circuit,

GUSTAV O." WILMS.

